In one method for splicing ends of optical fibers, there is a mechanical splicing system whereby ends of bare fibers of optical fibers are butted and mechanically fixed to each other with pressure. Ends of the optical fibers to be spliced are butted against each other and fixed with pressure inside a pressing fixing member equipped to a splice as a member for splicing the optical fibers. More specifically, the splice 10 shown in FIG. 15 includes the element 11, a jacket 12 for storing the element 11, end plugs 13-1 and 13-2 each of which has an optical fiber insertion opening 13a and can be fitted in an end of the jacket 12 for guiding the optical fiber, and a cap 14. The element 11 as a V-shaped foldable member holds the bare fibers of the optical fibers inserted from both ends thereof in a state in which both ends of the bare fibers of the optical fibers to be spliced are butt-jointed against each other. When fit to the jacket 12 and pressed down, the cap 14 brings the element 11 in the jacket 12 from an opening state shown in FIG. 16 to a closure state shown in FIG. 17. This operation presses and fixes the bare fibers 20a and 21a inserted in the element 11 as indicated in FIG. 18.
Before each optical fiber is inserted to the splice 10, each of the buffer coatings of the optical fibers is removed with the use of a buffer coating-removing tool by a length not smaller than a length to be fixed by the element 11, whereby the bare fibers 20a, 21a are exposed. A splicing process is from splicing the optical fibers with each other as above to storing the splice to an optical fiber storage tray.
During the splicing process, it is necessary not to twist or apply tension to the optical fibers so as to prevent the optical fibers from damage and connection loss. In other words, if the optical fiber extending from the element 11 is twisted or applied tension, the optical fiber is damaged or subject to loss by micro-bending. Although the bare fibers 20a, 21a of the optical fibers are secured with cramping inside the element 11, portions 22 near the element of the bare fibers 20a, 21a not retained by the element 11 can move freely, and therefore a stress by the twist or tensile force is possibly concentrated to the portions 22 close to the element.
For easing the above stress concentration to the movable portions 22 close to the element, U.S. Pat. No. 5,638,477 discloses an optical fiber splicing member having a function of grasping optical fibers at both sides of the element in an axis direction of the optical fibers. Specifically, as shown in FIGS. 19 and 20, clip members 17 are added to the structure of FIG. 15 for grasping buffer parts of the optical fibers. According to the optical fiber splicing member 30, the buffer part 25 is caught into a narrow gap portion 17a of the clip member 17 by pressing down both the cap 14 and the clip member 17 by a splicing tool at a splicing time. The buffer part 25 is held in this manner, so that the stress is prevented from being generated to the optical fiber at the end of the optical fiber extending from the element 11. A force (of holding the buffer part 25 by the clip member 17) is such that prevents the stress because of extension/contraction of the optical fiber in the axis direction thereof. If the holding force of the clip member 17 is too large, the extension/contraction of the optical fiber in the axis direction by an environmental temperature change cannot be allowed, and the stress is generated to possibly damage the bare fiber.
The structure revealed in U.S. Pat. No. 5,638,477 requires the clip members 17, which more or less complicates assembling the splicing member in a manufacturing process. Moreover, the clip member 17 is required to be pressed down to the inside of the jacket 12 as indicated in FIG. 20. The splicing with the use of the existing splicing tool as it stands is accordingly difficult work, urging some modifications to the splicing tool. While the buffer part 25 is retained in the narrow gap portion 17a of the clip member 17 as above, and since a breadth of the narrow portion 17a is unchangeable, the holding force of the clip member 17 to the optical fiber varies depending on whether the buffer part 25 has a large or small diameter due to manufacturing errors of the buffer part 25. It is feared that the buffer part of the optical fiber cannot be held stably at all times.